EP 2 006 471 A1 discloses a wind turbine tower comprising a number of segments with a polygonal cross-section, wherein each segment comprises a number of flat steel plates which are connected to each other so as to form the polygonal cross-section. Thereby, two plates are connected using a splice plate and using bolts to fix the splice plate at the flat steel plates of the segments.
However, it has been observed that a segmented wind turbine tower wall may have reduced stability under certain conditions and/or after longer operation times.
There may be a need for an apparatus to indicate a reduction of the stability of a wind turbine tower wall. Further, there may be a need for an apparatus for indicating a reason for a reduced stability of a wind turbine tower wall.